Variation in restriction maps in a 40 kilobase region surrounding the dopadecarboxylase structural gene (Ddc) has been examined in 50 second chromosomes from natural populations of Drosophila melanogaster. Restriction site polymorphisms indicate a level of sequence variability comparable to that seen in the Adh region. However, substantially fewer insertions and deletions are observed in the Ddc region. The significance of these patterns are being investigated through examination of Ddc gene activity and additional restriction mapping in flanking regions.